Yes, there are big differences between brokers, especially between MBTrading and Pepperstone (in our case). That is because the differences between the price feed, the spread and the commission. The spread is included in the robot code and it is used as an indicator.
We made a backtest with our jforex version of the robot on Dukascopy and the backtest result was almost identical with Alpari UK, better then MBTrading and worse than Pepperstone, that means that Pepperstone account is doing better than the backtest results...
Regarding MBTrading, I don't know if that's a rule, but as I see on FPA brokers reviews, old and famous brokers tend to worsen their services over time.
We just started a live test on demo accounts on our preferred brokers, to see which one is the best for our robots. The brokers are: FinFX (ECN account), ATCBrokers, HotForex (Currenex account), Oanda, FXOpen (ECN account) and Alpari UK (Spread Betting account).
The differences are visible on demo accounts also.
The statements will be published on our forum by the end of this month.
Ultimately, we are here to make profit trading on forex and not to trade with a specific broker. So if there is a broker with better results than other, why not chose the better one?
Yes, you can make those statements public, there is no problem with that.
It is important though to use the default settings, or, well, without much deviation from these settings and all 11 currencies.
And it is important also to run MT4 platform on a computer always connected to the Internet or on a VPS. If the robots are stopped during the day, or if they are interrupted while the market is open, the test is irrelevant.